Fire and smoke monitoring and alarm system

ABSTRACT

A monitoring and alarm system including a plurality of sensors located at various remote stations, each sensor being provided with a detector switch which is normally closed and which opens when any abnormal condition, such as fire or smoke is sensed. Each detector is connected by a two-wire line to a respective pair of terminals at a central console, across which is shunted an indicator lamp in series with a diode. The terminal pairs are connected in a series chain to a direct-current source, such that when all of the associated detector switches are closed, the chain is unbroken and the lamps are short circuited out of the chain, but when any detector is caused to open, the lamp associated therewith is then interposed in the chain and is energized through a flasher circuit to produce a pulsatory indication identifying the station responsible therefor.

United States Patent Levy [ Feb. 15,197

51 lnt.C1.

[54] FIRE AND SMOKE MONITORING AND ALARM SYSTEM [72] inventor: Marvin.1. Levy, .2131i 1en wood Place,

Bellmore, NY. 11710 ..G08b 17/00 [58] FieldofSearch.340/2271228,227,213,418

[ 56] References Cited UNITED STATES PATENTS Primary Examiner-Donald .1Yusko Assistant ExaminerWilliam M. Wannisky Attorney-Michael Ebert [57]ABSTRACT A monitoring and alarm system including a plurality of sensorslocated at various remote stations, each sensor being provided with adetector switch which is normally closed and which opens when anyabnormal condition, such as fire or smoke is sensed. Each detector isconnected lay a two-wire line to a respective pair of terminals at acentral console, across which is shunted an indicator lamp in serieswith a diode. The terminal pairs are connected in a series chain to adirect-current source, such that when all of the associated detectorswitches are closed, the chain is unbroken and the lamps are shortcircuited out of the chain, but when any detector is caused to open, thelamp associated therewith is then interposed in the chain and isenergized through a flasher circuit to produce a pulsatory indicationidentifying the station responsible therefor.

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FIRE AND SMOKE MONITORING AND ALARM SYSTEM RELATED APPLICATION Thisapplication is related to my copending application Ser. No. 818,677filed Apr. 23, 1969 on a Monitoring System for Door Stations.

BACKGROUND OF INVENTION This invention relates generally to monitoringand alarm systems, and in particular to a system in which the existenceof fire, smoke or any other abnormal condition is sensed at any stationin a multiple-station installation to produce a switching actionfunctioning to identify the responsible station at a central consolewhere an alarm is also given.

In one known form of tire alarm system, detector heads are placed atvarious stations throughout a structure, the heads all being linked bylines to a common alarm circuit. The heads, which are usuallyconstituted by bimetallic switches or equivalent elements aretemperature sensitive and operate in response to an abnormal rise intemperature to actuate the alarm circuit.

While in a system of this type, the alarm calls attention to a hazardouscondition somewhere in the structure, it does not actually identify theactivated detector and hence does not point to the location of the fire.This is a serious drawback when the installation is made in amultiple-story building, a large warehouse or in any other elaboratestructure, for precious time may be lost in finding the cause of thealarm.

To overcome these drawbacks, systems have been proposed in which eachstation detector is coupled to an indicator on a central annunciatorboard which identifies the activated dc tector. In such systems, when agiven detector switch is closed, current flows through the lineextending from the switch to the associated annunciator relay to actuatethe relay. The difficulty with this arrangement is that where thedetector lines are distributed among various stations throughout a largebuilding or other installation, the length of the lines may introducesubstantial resistance in the circuit. Consequently the voltageestablished at the annunciator board may fall below the value necessaryto actuate the associated indicator relay.

While it is possible to compensate for the effect of line re sistance,the resultant arrangement becomes relatively complicated and costly.Moreover, in some situations, particularly where the lines go through anenvironment which may contain explosive gases or chemicals, thecurrent-carrying lines themselves constitute a possible hazard, for thecurrent therethrough is relatively heavy and might produce sparking atthe detector contacts or elsewhere in the line should there be a failurein line insulation.

BRIEF DESCRIPTION OF INVENTION Accordingly, it is the main object ofthis invention to provide an improved alarm system in which a pluralityof sensors at various remote stations are coupled by individual lines tolights or other indicators on a central console so that the existen'ceof an abnormal condition at any station is indicated at the console andan alarm given.

More specifically, it is an object of this invention to provide a systemof the above type, in which the status of each station is indicated bymeans of individual light indicators, a single relay and alarm devicecommon to all stations, whereby the sounding of the alarm alerts asupervisor who then, by viewing the indicators, can identify theresponsible station or stations.

Also an object of the invention is to provide an alarm system of simple,reliable and efficient design, which may be manufactured at low cost andwherein the lines extending from the central console to the stationsoperate at very low current and voltage levels and offer no danger tobuilding personnel. Nor do these lines constitute a fire hazard.

The invention has many practical applications, for the detectors at thevarious stations may be made sensitive to fire, smoke, gas or any otherabnormal condition, or in the alternative, the detectors may be maderesponsive to an unauthorized entry, such as at a window or door.

Briefly stated, these objects are accomplished in an alarm system inwhich a plurality of sensors located at remote stations each includes anormally open detector switch which closes only when an abnormalcondition, such as fire, arises. Each detector switch is connected by anextended two-wire line to a respective pair of terminals at a centralconsole.

Across each pair of terminals is shunted a lamp in series with a diode.The terminal pairs are connected in a series chain to a voltage sourcewhereby when all associated detector switches are closed, all lamps arebypassed thereby and the chain is unbroken, but when any detector switchis open, the lamp associated therewith is is then interposed in thechain and is energized through a flasher unit to produce a pulsatinglight indication identifying the station responsible therefor. Thearrangement is such that when a lamp is energized, an alarm is alsoactivated to alert a supervisor at the console location.

BRIEF DESCRIPTION OF DRAWING For a better understanding of theinvention, as well as other objects and further features thereof,reference is made to the following detailed description to be read inconjunction with the accompanying drawing, wherein:

FIG. t is a perspective front view of the console included in an alarmsystem in accordance with the invention;

FIG. 2 shows the console from the rear and the line connectionstherefrom to detectors at remote stations; and

FIG. 3 is a schematic circuit diagram of the system.

DESCRIPTION OF INVENTION Referring now to FIGS. 1 and 2, in :an alarmsystem in accordance with the invention, a central console 10 isinstalled in a control booth or at any other supervisory position, abank of lamps L-l to L-10 being mounted on the front panel thereof. Eachlamp represents a respective remote station (I to X), and serves toindicate the status of its associated station. It is to be understoodthat while ten lamps are shown, in practice the system may include asmaller or larger number of stations and a corresponding number ofindicators at the console.

A row of 10 terminal pairs T-l to T-'-10 is mounted on the rear of theconsole, each pair corresponding to a lamp and being connected by atwo-wire line (L to L to sensors D, to D,,, respectively, at remotestations I to X, placed at various points throughout the building orwherever else the installation is made. Thus in a motel having 10)units, a sensor may be placed in each unit, the console being installedin the office. The length of the line wires is not a factor in theoperation of the system, and light-gauge wire may be used.

Each sensor (D, to D includes a normally open detector switch which iscaused to open in response to an abnormal condition. Thus in the case ofa fire alarm system, the switches may be operated by bimetallic elementsadjusted to cause the associated switch to open only when thetemperature at the station rises above a preset level.

In practice, the fire detectors may be associated with a sprinklersystem. In a sprinkler system, a sprinkler head coupled to a waterlineis provided with a thermally sensitive fusible valve lock which meltswhen the ambient temperature rises above a safe level, thereby releasingthe flow of water to extinguish the fire. By the time this happens, thetire may be fairly well advanced, and the release: of the sprinkler maycause water damage.

By clipping or otherwise linking a detector switch to a sprinkler headand setting the detector so that its switch closes at an abnormaltemperature level, which 'is nevertheless somewhat below the level atwhich the sprinkler loclt melts, the supervisor at the control consolemay be alerted to a dangerous condition at a particular station and bein a position to take steps to correct this condition before thesprinklers are activated.

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The detectors at the various stations may be made sensitive to any othercondition, such as gas, noise, moisture, or whatever other factor is tobe monitored. The system can also be made to operate as a burglar alarmby so arranging the detector switches at points of entry in a buildingthat the switch is caused to open only when an unauthorized entry ismade, the associated lamp at the console identifying this point.

' Mounted within the console, is an alarm such as buuer BZ, which isactivated when any one of the lamps is caused to operate. The alarmserves to alert the supervisor, so that by locking at the lamp bank onthe panel, he will be advised of which station is responsible for thealert.

Referring now to FIG. 3, the electrical circuit of the system is shown,power therefor being supplied by a power supply including a stepdowntransformer 11, whose primary 11A is connected through a master switch12 to the AC powerline. The secondary-11B of the transformer isconnected to a fullwave rectifier network provided with diode rectifiers13 and 14 to produce a DC output (12 volts) at output terminals DC+ andDC. Alternatively, the necessary power for operating the system may beprovided by batteries.

A single relay RL is provided for operating all of lamps L-l to L-10.The relay includes a solenoid 15 which, when energized, simultaneouslyactuates four ganged switch sections 8,, S S and 5,, each of which hasan armature M, an upper fixed contact A, and a lower fixed contact B. Inthe deenergized state of the relay, the armatures M all engage their associated upper contacts A, the armatures being pulled over the lowercontacts B only when solenoid 15 is energized.

Each pair of terminals (T-l to T-10) is connected by its related line (Lto L to a respective detector switch (D to D,,,) at a remote station, (1TO X), but in the event less than the total number of availableterminals is in use, the unused terminal pairs are each shunted by ajumper, such as jumper 16, across terminal pair T10. The terminal pairsare connected in series between points X and Y to form a series chain,and when all terminal pairs are shunted by closed detector switches orjumpers, the series chain is unbroken to provide a conductive path whichextends through all of the associated lines L,, L,, etc.

Each lamp is connected in series with a respective diode LD1, LD2, etc.,across the correspondingly numbered terminal pair T-1, T-2, etc., andsince each detector switch D,, D,, etc., associated with the tenninalpair is normally closed, the series lamp circuit thereacross iseffectively bypassed in the series chain. Point X in the series chain isconnected to armature M of switch section 5,, while point Y is connectedto armature M of switch section 8,.

A flasher unit is provided to operate the lamps intermittently (i.e.,one-half second on, one-half second off). This unit comprises a flasherrelay RF whose solenoid 17 is connected to a unijunction solid-staterelaxation oscillator constituted by transistors 18 and 19, resistors20, 21, 22, and a capacitor 23. The RC time constant of the circuit issuch as to energize solenoid 17 at the desired flashing rate.

Solenoid 17 of the flasher relay actuates a single switch section S,having an armature M, an upper fixed contact A, and a lower fixedconstant B, the armature normally engaging contact A. One end of therelaxation circuit is connected through conductor 24 to the negativeterminal DC- of the voltage source, while the other end is connectedthrough conductor 25 to armature M of switch section 5,, whose A contactis connected to the A contact of switch section S of the lamp relay RL.

Buzzer B2 is AC operated and is connected across one-half of transformersecondary 11B through armature M and contact A of switch section 8,.Hence, at the outset, when relay RL is deenergized, the AC buzzercircuit is completed and the buzzer sounds. A'pilot light 26, located onthe front panel of console 10, is connected directly across the sameone-half of secondaryllB; hence when master switch 12 is closed, thepilot light is energized to indicate that the console is operative.

A reset switch button 27 is connected between positive supply tenninalDC+ and through diode 28 to the upper end of solenoid 15 of relay RL thelower end of which is permanently connected to the negative supplyterminal DC. Thus when reset button 27 is momentarily depressed, the DCoutput of the supply is applied across the solenoid and relay RL ismomentarily energized, by the full output of the DC power supply,causing armatures M of switch sections S to S, to engage theirrespective B contacts. Since the buzzer circuit is connected to its ACsource through contact A of switch section the energization of relay RLbreaks the buzzer circuit and silences the buzzer.

Momentary energization of relay RL completes a holding circuit therefor,this circuit being constituted by contact B and armature M of switchsection 8,, which connects the upper end of solenoid 15 to point Y ofthe series chain, point X of the chain being then connected througharmature M and contact B of switch section S to the positive terminalDC+.

It is important to note that lamp relay RL is initially energized by DCvoltage passing through reset button 27 and derived directly from thesupply in the console, but when the holding circuit takes over tomaintain the relay in the energized state, current through solenoid 15is then by way of the series chain at points X and Y and hence is by wayof all of the external lines L L etc., associated therewith.

The fact that these external lines may be very long and thereby serve tointroduce a significant amount of resistance in the holding circuit,does not mean that relay RL will not be held. The reason for this isthat it takes a significantly lower voltage to hold in a relay, onceenergized, than to effect the initial actuation thereof, for in thelatter case, the inertia inherent in the relay must be overcome, andonce overcome less voltage is necessary. For example, while it takes 12volts to initially actuate the relay, it may take as little as 4 or 5volts to maintain actuation thereof.

Consequently, in the holding state, current flows through solenoid 15 ofrelay RL and through all closed detector switches D D etc., (orequivalent jumpers), by way of the extended lines L L etc. The level ofcurrent flow through these lines is very low and is not, therefore,hazardous in any way.

When, as a resultof a fire at any one of the stations or any othersignificant change in status which affects the sensor at that station,the associated detector switch is caused to open and the series chainbetween points X and Y is broken. When this happens, the lamp and diodecombination related to the open detector switch is then interposed inthe chain.

For example, if detector switch D opens, then lamp L-l and diode LD-l inseries therewith are interposed in the series chain between points X andY, thereby substantially increasing the resistance offered by the serieschain and causing the voltage applied to solenoid 15 of relay RL to fallbelow the holding level.

When this occurs, relay RL is deenergized, in which event the flasherunit conductors 24 and 25 are then connected across the DC output atterminals DC- and DC+, for conductor 24 is permanently connected tonegative terminal DC, whereas conductor 25 is now connected by contact Aand armature M of switch section S, to positive terminal DC+. When theflasher unit is energized, switch section S, then proceeds to open andclose periodically.

Switch section 8,, which opens and closes periodically, acts to applythe battery voltage from terminals DC+ and DC- across the series chainat points X and Y which now have lamp L-l and diode LD-l interposedtherein.

It will be seen that point Y is connected through armature M and contactA of section S, of the deactivated relay RL to positive terminal DC+. Itwill also be seen that point X is connected through armature M andcontact A of Section S, of relay RL through the armature M and contact Aof section S, of flasher relay RF, and from there through acurrent-limiting resistor 29 to the negative terminal DC. Hence voltagefrom the DC supply will now flow at a periodic rate determined by theaction of the flasher unit, through lamp L-ll, which is interposed inthe series chain between points X and Y.

At the same time, since relay RL is deactivated, buzzer BZ sounds analarm, for it is now energized through armature M and contact A ofswitch section 8,. Thus the opening of detector switch D at the firstremote station I is indicated by the pulsing of lamp L-ll, accompaniedby the sound of the buzzer.

If another detector switch opens, say detector switch D at station VI,when detector switch D is already open, lamps L-l and L-6 will thenboth, be illuminated, but in this instance the operating current flowingthrough the chain between points X and Y is shared by these lamps, hencethe lights will be somewhat dimmer.

In order to test the system to see whether it is functioning properly, anormally closed test switch 30 is provided between contact B of switchsection S, and the upper end of solenoid of relay RL, such that when therelay RL is held by the holding circuit including this switch section,the holding circuit may be broken by opening test switch 30 to be surethat the relay will then drop out.

Because the system can tolerate resistance in the holding circuit, thelines L L etc., may be of light-gauge wire, for the current carriedthereby is of very low level and need not be heavily insulated.

While there has been shown and described a preferred embodiment of analarm system in accordance with the invention, it will be appreciatedthat many changes and modifications may be made therein without,however, departing from the essential spirit of the invention.

What 1 claim is:

l. A monitoring system comprising:

A. a plurality of sensors located at various remote stations, eachsensor including a normally closed switch and sensing means to causesaid switch to open when an abnormal condition is detected, and

B. a console at a central supervisory location, said console including:

a. a bank of terminal pairs equal in number to said sensors,

b. a two-wire line linking each station switch to a correspondingterminal pair,

c. a like bank of voltage-responsive indicators, each having asubstantial resistance and being connected across a correspondingterminal pair,

(1. a voltage source for said indicators, said source providing apredetermined voltage,

e. a relay having a solenoid, for operating all of saidvoltage-responsive indicators, said relay having four ganged switchsections including normally open holding-circuit contacts and normallyclosed switching contacts, said relay having an inherent inertia andrequiring said predetermined voltage initially actuate said relay, whichpredetermined voltage is sufficient to overcome said inertia and issubstantially higher.than the holding voltage thereafter necessary tohold the relay in the actuated state,

f. switching means connecting said source directly to said solenoid toapply said predetermined voltage thereto to actuate said relaymomentarily and thereby to open said switching contacts and to closesaid holding circuit contacts,

g. means connecting said terminal pairs in a series chain to saidvoltage source through said holding-circuit contacts whereby saidindicators are bypassed when the associated station switches are closedto produce a holding voltage holding said relay in the actuated state,said indicators being interposed in said chain when said switches areopen, whereby when a given switch is open the corresponding indicator isactivated to identify the responsible station, said activated indicatorintroducing said substantial resistance in said series chain, whichresistance has a value reducing the voltage applied by said holdingcircuit to a point below said holdin voltage and thereby effectingdeenergization of sai relay whereby said relay switching contacts arecaused to close, and

h. means to apply a voltage derived from said source through said closedswitching contacts to said chain to operate the activated indicator.

2. A system as set forth in claim ll, further including an alarm device,and means to activate said device when any one of said indicators isactivated.

3. A system as set forth in claim ll, wherein said sensors are thermallyresponsive elements sensitive to tire.

4. A system as set forth in claim 3, wherein said elements are attachedto sprinkler heads also having thermal elements, the thermal elements ofthe sensors being activated at a lower temperature than those of saidsprinkler heads.

5. A system as set forth in claim 1, wherein said indicators are eachformed by a lamp in series with a diode.

6. A system as set forth in claim 1, further including a flasher unit toprovide a pulsatory indication, and constituted by an auxiliary relayadapted to make and break a switch interposed between the chain and thesource, said auxiliary relay being energized periodically by arelaxation circuit connected to said source, said flasher unit beingactivated when said switching contacts of said relay are closed.

1. A monitoring system comprising: A. a plurality of sensors located atvarious remote stations, each sensor including a normally closed switchand sensing means to cause said switch to open when an abnormalcondition is detected, and B. a console at a central supervisorylocation, said console including: a. a bank of terminal pairs equal innumber to said sensors, b. a two-wire line linking each station switchto a corresponding terminal pair, c. a like bank of voltage-responsiveindicators, each having a substantial resistance and being connectedacross a corresponding terminal pair, d. a voltage source for saidindicators, said source providing a predetermined voltage, e. a relayhaving a solenoid, for operating all of said voltage-responsiveindicators, said relay having four ganged switch sections includingnormally open holding-circuit contacts and normally closed switchingcontacts, said relay having an inherent inertia and requiring saidpredetermined voltage initially actuate said relay, which predeterminedvoltage is sufficient to overcome said inertia and is substantiallyhigher than the holding voltage thereafter necessary to hold the relayin the actuated state, f. switching means connecting said sourcedirectly to said solenoid to apply said predetermined voltage thereto toactuate said relay momentarily and thereby to open said switchingcontacts and to close said holding circuit contacts, g. means connectingsaid terminal pairs in a series chain to said voltage source throughsaid holding-circuit contacts whereby said indicators are bypassed whenthe associated station switches are closed to produce a holding voltageholding said relay in the actuated state, said indicators beinginterposed in said chain when said switches are open, whereby when agiven switch is open the corresponding indicator is activated toidentify the responsible station, said activated indicator introducingsaid substantial resistance in said series chain, which resistance has avalue reducing the voltage applied by said holding circuit to a pointbelow said holding voltage and thereby effecting deenergization of saidrelay whereby said relay switching contacts are caused to close, and h.means to apply a voltage derived from said source through said closedswitching contacts to said chain to operate the activated indicator. 2.A system as set forth in claim 1, further including an alarm device, andmeans to activate said device when any one of said indicators isactivated.
 3. A system as set forth in claim 1, wherein said sensors arethermally responsive elements sensitive to fire.
 4. A system as setforth in claim 3, wherein said elements are attached to sprinkler headsalso having thermal elements, the thermal elements of the sensors beingactivated at a lower temperature than those of said sprinkler heads. 5.A system as set forth in claim 1, wherein said indicators are eachformed by a lamp in series with a diode.
 6. A system as set forth inclaim 1, further including a flasher unit to provide a pulsatoryindication, and constituted by an auxiliary relay adapted to make andbreak a switch interposed between the chain and the source, saidauxiliary relay being energized periodically by a relaxation circuitconnected to said source, said flasher unit being activated when saidswitching contacts of said relay are closed.